Cardiovascular risk factors at age 30 following pre-term birth

Abstract

Background: Recent epidemiological evidence has shown increased rates of cardiovascular mortality and associated risk factors in those born small. However, scarce information exists concerning cardiovascular risk factors in adulthood following pre-term birth, or distinguishing the relative contributions of length of gestation and fetal growth to small size at birth.

Methods: Prospective follow-up of 458 30-year-olds whose mothers took part in a randomized controlled trial of antenatal betamethasone for the prevention of neonatal respiratory distress syndrome (147 born at term, 311 born pre-term). Follow-up assessments included anthropometry, blood pressure, blood lipids, early morning cortisol levels and 75 g oral glucose tolerance test.

Results: Gestational age at birth, pre-term birth, and birth weight z-score were not associated with serum cholesterol, triglyceride or cortisol at age 30 (P > 0.1 for all). However, pre-term birth was associated with increased systolic blood pressure (3.5 mmHg, 95% CI 0.9-6.1 mmHg, P = 0.009) and insulin resistance at age 30 [Log (Insulin area under the curve) = 0.17, 95% CI 0.05-0.28, P = 0.006]. Low gestational age at birth was also associated with these outcomes, whereas birth weight, adjusted for gestational age, was not.

Conclusions: Adults who were born moderately pre-term have increased blood pressure and insulin resistance at 30 years of age. Pre-term birth rather than poor fetal growth is the major determinant of this association. As both the incidence of pre-term birth and survival amongst those born pre-term are increasing, this group may contribute an increasing proportion to overall cardiovascular disease burden.